Generally, an endoscope for medical use has an elongated flexible insertion tube extended forward from a manipulating head grip for insertion into a body cavity. On the proximal side away from the flexible insertion tube, a universal connection cable is led out from the manipulating head grip for connection to peripheral units. An endoscopic observation means including an illumination window or windows and an optical observation window is provided at a fore distal end of the endoscopic insertion tube thereby to observe and examine an intracavitary site of interest. In case a lesion is spotted as a result of an endoscopic examination, it may become necessary to give a suitable treatment to the lesion or to sample a cellular specimen or specimens. For this purpose, a tool guide channel is usually provided on a medical endoscope to extend between a tool entrance way, which is provided on a manipulating head grip of the endoscope, and a tool exit opening which is provided at a fore distal end of the elongated insertion tube of the endoscope. Since the elongated insertion tube of the endoscope has to be flexible in bending directions, the tool guide channel is normally constituted by a tube which is also flexible in bending directions of the insertion tube.
Examples of bioptic or surgical tools to be introduced into a body cavity by way of a tool guide channel on an endoscope include, in addition to forceps such as bioptic forceps and grasper forceps, high frequency tools such as high frequency knife or snare, cytodiagnostic brush and shadowing agent feeder tube. In tools of this sort, a manipulation handle is attached at a proximal end of a tool, and functional action parts of the tool are mounted on a distal end of a flexible cord from the manipulating handle. The surgical or bioptic tool is placed in a tool guide channel on an endoscope through an entrance way on a manipulating head grip of the endoscope, and pushed forward to protrude out of a tool exit opening at the distal end of an elongated insertion tube of the endoscope over a certain length for necessary for giving a required treatment.
For example, in case of a high frequency tool like a high frequency knife with a rod-like electrode member or a cytodiagnostic brush, there is no need for orienting the tool to a particular radial direction upon protrusion from a tool exit opening at the distal end of the tool guide channel on the endoscopic insertion rod. However, forceps as well as shadowing agent feeder tube needs to be oriented toward a specific radial direction at the time of protrusion from the tool exit opening. More specifically, in the case of forceps having a pair of grasping jaw members operably connected to a flexible cord, it is necessary for the forceps to be correctly oriented to a radial direction facing toward a target point of treatment for performing a required function as soon as it is protruded out of a tool exit opening at the end of the tool guide channel. In this regard, from the standpoint of improving maneuverability of a surgical or bioptic tool, a functional action mechanism of a tool should be adjustable in radial directions at the time of protrusion from the tool exit opening. Similarly, a high frequency tool like a high frequency knife as well as a high frequency snare requires an adjustment to a particular radial direction depending upon the shape of the tool.
The radial orientation of functional action elements of a tool should preferably be made by remote control from a position rearward of a tool entrance way on a manipulating head grip of an endoscope. In this regard it is difficult to directly turn a flexible cord of a tool clockwise or counterclockwise from that position in such a way as to transmit a clockwise or counterclockwise rotation correctly to the action elements at the distal end of the flexible cord. The radial or angular orientation of functional action elements of a tool becomes extremely difficult especially in a case where outer surfaces of a flexible cord of a tool are left in frictional contact with inner surfaces of a tool guide channel.
In this connection, disclosed in a Japanese patent application laid open under 2005-34623 is a tool orientation mechanism in which a sheathing tube is fitted relatively rotatably around an insert tube having forceps members attached to a fore distal end of a flexible cord which is in turn connected to a manipulation member at its proximal end thereby to rotate the insert tube relative to the sheathing tube. In this case, when the manipulation member is rotated relative to the sheathing tube, its rotation can be transmitted securely to the forceps members at the distal end of the flexible cord to orient the action elements to a particular radial or angular direction.
By the way, in the case of an endoscopically inserting a bioptic or surgical tool, it is a must for the flexible cord of the tool to have a length which is sufficient enough for letting a functional action element of the tool protrude out of a tool exit opening at the end of the tool guide channel over a length necessary for performing a required function. For this purpose, it is the general practice for such a tool to have a flexible cord which is longer than the endoscopic tool guide channel in total length. In addition, in order to be adaptable to a diversity of endoscopes with insertion tubes of different sizes, generally an endoscopically inserting tool is attached with a flexible cord which is way longer than a tool guide channel on an endoscope. That is to say, a manipulation member at the proximal end of a tool is necessarily located at a distant position from a tool entrance way on a manipulating head grip of an endoscope, necessarily leaving a proximal end portion of the flexible cord freely in an open air rearward of the tool entrance way over a redundantly large length which would cause flexural deformations to the flexible cord to such a degree as to make it difficult for an operator or nursing staff to orient the tool to an aimed or intended direction by way of the manipulation member at the proximal end of the flexible cord.